Check out this thread -- scroll down a few pics to get to an XD that has a "stainless" duracoated slide.
Duracoat Pictures - Maryland Shooters
The guy who did those is also doing some X-FIVE parts for some of my projects (the KWC X-FIVE and X-FIVE open)
The metallic colors will not be shiny like a chrome plating, they look more like matte metallic finish. Better than a gray color but not a shiny finish.
You actually CAN chrome plate pot metal (you can even chrome plate plastics too) but the quality of the finished job depends partly on what you chrome--mostly on the person who is doing the stripping and dipping. Also items that flex, like plastic car trim that is chrome plated, allow the plating to eventually flake off.